A homologue of dystrophin is expressed at the neuromuscular junctions of normal individuals and DMD patients, and of normal and mdx mice. Immunological evidence.

Polyclonal and monoclonal antibodies, which recognize different regions and epitopes of the dystrophin molecule, bind to a protein of Mr 400,000 which is present in extracts of mdx muscle from regions which contain neuromuscular junctions (NMJ) and is absent from those which do not. This NMJ-associated homologue of dystrophin has at least 2 epitopes which are different to usual Xp21 form of dystrophin expressed along the sarcolemma of muscle fibres in normal muscles. This protein is also expressed at the NMJ of a DMD patient who lacks the first 52 exons of the Xp21 dystrophin gene and it must therefore be translated from a different gene transcript.